The purpose of this study is to determine whether improvements of axial mobility result in improvement of function of older individuals. Axial mobility refers to motion and flexibility of the neck, back, and pelvic complex; function includes performance of simple activities (lying down to sitting up), general ability for activities of daily life, and overall disability. Older individuals include sedentary elders and persons 55 or older who have Parkinson's disease. Two substudies have been completed and manuscripts are in preparation: 1. Physical Intervention for People with Parkinson's Disease: Losses of axial mobility can be a contributing factor in the loss of agility and functional capability of individuals who have Parkinson's disease (PD). This randomized clinical trial in- vestigated the efficacy of an experimental exercise protocol designed to improve axial mobility (mobility of the neck and back) and functional performance (e.g. lying down to standing up; gait) of individuals who have PD. Subjects were randomized into two groups. The intervention group was treated for ten weeks, three times per week, using a protocol that was designed to improve axial and extremity flexibility and coordination of movement. The usual care (control) group did not receive a specific exercise program but was measured at baseline and at ten weeks. Outcome measures to determine efficacy of intervention included: 1) range of motion of the neck and back; 2) functional capability including functional reach (a measure of balance control), and timed functional movements (e.g. coming from supine to standing). Results demonstrated changes in axial mobility as well as physical performance including two measures of axial mobility and two measures of physical performance (functional reach and number of steps to complete a 360 degree turn in standing (a measure of ability to coordinate movement in standing). In addition, all subjects who participated in the control arm of the study subjects were invited to participate in the intervention. Forty five of the 46 subjects did so. Data demonstrated changes in a number of measures of flexibility and physical performance. In conclusion, the results of this study demonstrate that exercises provided in the early and middle stages of PD can reverse some of the losses of flexibility that accompany the disease and improve the patient's ability to perform selected tasks that are critical to daily life. A follow-up study will be designed to further investigate issues such as best method for delivery of exercises and best approach to exercise intervention. 2. Measurement of Function: There is tremendous need for objective measures that can be used to assess functional change for older individuals. In order to be effective for use in research studies, it is necessary for measures to have good inter-rater reliability and adequate stability over time. To date, little is known about reliability, stability, and group specificity of a variety of measure. We have completed studies comparing a number of physical performance and impairment measures (e.g. supine to stand time, extremity strength, spinal configuration, and lumbosacral motion (flexion/extension) applied to community dwelling elders, those in early and mid-stage Parkinson's disease, and nursing home residents. Results of these studies indicate that these measures can be applied reliably by different researchers and that they are stable for both short and long intervals. These measures may be useful for detecting change in client performance over time.